The present invention relates to a disk array incorporating different kinds of disk drives. More specifically the present invention relates to a disk array which, in the event of a failure of a part of the disk drives, can perform sparing by using different kinds of disks and also to a sparing method.
A disk array accommodates a large number of disk drives. Should a part of these disk drives fail, a normal operation of the disk array cannot be guaranteed. As a means for improving a fault tolerance of the disk array, sparing may be used. The sparing involves preparing spare disk drives in a disk array in advance and, when a failure is detected, quickly disabling the failed disk drive and placing a spare disk drive in operation. After sparing is effected, an anomaly is notified to an administrator to prompt him to perform a maintenance service. By replacing the failed disk drive with a normal spare disk drive in this manner, the disk array can be maintained without stopping its operation.
JP-A-5-100801 discloses a technique which, when the number of access errors in a disk drive exceeds a predetermined value, disables the disk drive preventively before it fails and swaps it with a spare disk drive. JP-A-2002-297322 discloses a technique which, in the event of a failure, distributively stores data from the disabled disk drive in a plurality of spare disk drives.